Weight transferring supporting structure



March 15, 1960 H. w. RocKwELl.

WEIGHT TRANSFERRING SUPPORTING STRUCTURE Filed June 2, 1958 2 Sheets-Shee l March l5, 1960 H. w. RocKwELl.

WEIGHT TRANSFERRING SUPPORTING STRUCTURE Filed June 2., 195s 2 Sheets-Sheet 2 ilnited States,

" Y WEIGHT TRANSFERRING SUPPORTIN STRUCTURE This invention relates to earth moving vehicles and more particularly to an improved weight transferring supporting structure to be lutilized intermediate tractor and trailer units.

This invention is to be used with vehicles employed in road building operations wherein at various times the vehicles are operated over level hard surfaced terrain and at other times over rough terrain wherein varying surface contours and soil conditions present correspondingly varying load and traction problems.

It has been found desirablein the earth moving industry to increase the capacity of `the earth mover. It is advantageous to increase the capacity ofthe earth mover. by increasingthe size of the trailer unit without; increasing the :size of the tractor unit. Although the invention contemplates use with any type tractor unit, the invention will herein be described in conjunction witha two wheel tractor.

It is a general object of my herein described invention to use a relatively small two wheel tractor unit withan oversized trailer unit.v This gives rise to a problem in that when the earth mover is fully loaded and traveling at high speeds the enlarged capacity trailer places a sustained additional load on the tractor which adversely affects the life of the axle, axle bearings and axle housing with entailing danger of failure of parts.

To achieve safe loading of the tractor axle when the earth mover is fully loaded and traveling Aat high speeds: I found it desirable to introduce a load supporting structure having a pair of load bearing wheels mounted `in; termediate the tractor and trailer units. Since traction is a product of Weight von the driving wheels and the traction factor of the tireswith the ground, the removal, of Weight from the tractorV axle to permit safe operationY of the earth mover when fully loaded and operating at high speeds presents a problem of obtaining a suflcient amount-of traction when the earth mover is operating over terrain having varying contours and soil conditions and particularly during loading when a scraper unit is employed as the trailer. I found it desirable to provide aweight transferring means that is capable of selective ly transferring weight to the tractor unit when addi-v tional traction is required and in which the weight trans-` ferring means can be made inactive during other periods ofoperation so as not to interfere-with the operation of the ,earth mover when weight Itransfer is not beingutilized. :i n Previously constructed weight transferring means have` included provision for a hydraulic ram to be utilized for transferring weight to the tractor unit at certain periods of :operation when additional traction is needed and during other periods of operation the ram is placed in a iloat condition so that the ramwill not interfere with the opat moderate Ito high Aspeeds as when on a return trip with the trailer unit empty, with the hydraulic ram in theoat position, the piston would freely reciprocate in thel cylinder as the tractor and trailer units oscillated relative, to one another abouttheir transverse hitch axis. Thisrepetitious reciprocating of the piston adversely affects the wall,piston, rod and packing of the ram. Also, when the ram is in the float position and the tractor andV trailer units are oscillatingV relative to one another when traveling over bumpy terrain a'sudden build-up of pressure in the ram may occur which would cause the ram to interfere with the operation of the earth mover and cause undesirable heating of the oil.

Another means for overcoming the lack of traction includes the addition of weight to the tractor unit. Thsj provision for. additional weight to be attached to the tractor unit presents the problem of overloading the vtractor thereby overstressing various load supporting parts for sustained periods. Also, the use of weights would entail a considerable loss of operating time for mounting and dismounting the weights as needed.

As hereinbefore mentioned sustained additional loads on the tractor when the earth mover is operating fully loaded and at high speed, subjects the tractor load sup porting parts to excessive stresses. However, ordinarily during the operation of the earth mover, weight transfer would be used at slow-speeds and when additional trac-v tionY is lrequired. Thus, during weight transfer staticloads would constitute most of the load placed upon the tractors load supporting parts and these parts would not be in danger of failing due to excessive stresses which would occur if the parts were simultaneously subjected to dynamic loading caused by bouncing over rough ter` rain and the like.

Therefore it is an object of my invention to provide a wheeled load supporting structure to be used intermediate tractor and trailer units respectively which will carry the load which would otherwise be carried by thetractor unit.

It is a further object of my invention to provide aV 4 wheeled load supporting structure to be used intermediate tractor and trailery units respectively, wherein power means are selectively operable to transfer Weight from the load supporting structure -to the tractor when the vehicle is operating at slow speeds thereby placing static loads upon the tractor unit.

-' of theweight from the load lsupporting structure to the tractor unit.

It is a further object of my invention to provide a wheeled load supporting structure to be used intermediate tractor and trailer units respectively, wherein when the hydraulic ram is contracted the piston will not re,

eration of the earth mover when weight transfer is not being utilized. This provision hascontributed to increasing the traction of the earth mover; however, therranr` was so positioned' that when the earth mover'was-opf .l

erating with sufficient traction over bumpy terrain and ciprocate during relative oscillation of the tractor andI trailer units.

` It is'a further object of my invention to provide a wheeled load supporting structure to be used intermedi-, ate a single axle tractor unit and Wheeled trailer unit; respectively which will carry the load which would other,y wise be carried by the tractor unit. v f It is a further object of my invention to providel a wheeled load supporting structure -to be used intermediate a single axle tractor unit and wheeled trailer unitI respectively, wherein power means are selectively opferable to transfer Vweight from the load supporting struc; ture to thetractor when the vehicle is operating at slow speedsthereby placing static loads upon the tractor unit.; It is a further object of my inventionl to provide a wheeled load supporting structure to be used intermedi Patented Mar. 15, 19'3 0 -a o the tractor and trailer units;

These and other objects and advantages of iii/ven# tion will be evident when the following description isV read in conjunction with the accompanying drawings; in'4 whicliz' Fig. l isl aside viewf of aunitf comprising' tractor and trailer units and embodying the invention;

Y Fig. 2 is a planeview of the same as shown in- `Figi- Il;

Fig. 13 is an enlargedside view, partly insection; of.' the rearwardl portion of the tractor unit;- the embodied invention: and the-forward portion of the tl'ailer'unit; and

Fig; 4 is an enlarged side-view, partly in section,- o'f' the# rear portion of the tractor and thev forward portion of' the1 trailer with theA embodied invention` inalweight trans# fer-ring' position.

magma the trailer hitch support 25 by pins 34 and 34 respectively.' The branches pivot about a transverse axis 36 which is spaced from, parallel with and below the axis 35 of wheels 23. Disposed between the branches 32 and 32 ofzthe fork frame is a power means illustrated as a double acting hydraulic ram 38. The ram 38 is supplied with iluid pressure from any `suitable source (not shown) and is controlled by the operator ofthe vehiclef The ram 38 is pivotally cor'iriectedl to extensions 30 of the pedestal portion 31 by a pin 3' 7 and the opposite end of the ram 3S is pivotally connected to a lever afin 39" by a pin- 41: When the' ram'` iseontracteditie in its noriweight transferring position and when expanded it is in its weight transferring position as shown iin= Fig. 4 The lever arm 39 is also disposed between branches 32 and 32 and is pivotally connected toV ears 42- of tll'e'= trailer hitch support y 25 by a prin 43 for pivotal movement about the common transverse axis 36 from a nonabutting position corresponding to the nonweighttransferring position ofthe Referring to `l this invention isembodied in af 'i small site two wheel tractor 10E and an* oversized two" wheel trailer 15. The tractor 10 includesaI- pair of tractionl wheels 11, a main f-rame12 anda; hitchrnember' 1-3a- Hitch 13 isi pivotally connected to main' frame' 1l2j atL Mi (f'showni in Fig; 2)' and 45A for rocking" movement abt the-longitudinal pivot axis of pinv 46\. It' Will-bereadily apparent, however, that the connections"y 'atl' 44 and- 45 are'i such: that? hitch member 13= is-lreld' rigidly' against for@ and'aftT pivotal movement'with respectto thetfifacto rn'a'ini frame 12. The tractor is provided with an engine 154 supplying suitablepower for towing' the trailer 15a.

` The trailer 1S includes a bowl" frame. 16,` ayoke"l 1'7- having: a forward` pedestal 22 andi a pair-of rearwardl-'yi extending side arms 18 pivotally connected bypin's119f to the bowl frame 16, and a pair of supporti wheels: 21.

The attachment` of the oversize trailer 15-1tothe'- r'e`la-k tlively smaller size' tractor 1'0 would placeY excessive stresses on the loadsupportingVv partsA of the tractor 130i' The subjection of the load supporting parts of the tractorV I0 toEV excessive stresses is. particularly/detrimental tothe life: thereof? when the vehicle is traveling over roughy terrain which causes the earth mover' t'o bounceon ita inatedl tires, thus'Y placing dynamic loade oni the`= load supporting" parts ofl theftractor. A load supporting stm'c" tu'r'e 201 is` mounted intermediate the tractor? andltrailer units, and carries the load whichy Wouldlother'vvise bef carriedl by the load' supporting oftheltrac'torf unit, thirs`=providing a safe load on thetracto'r. uniti Thello'ad supporting structure 20" includesa` trailerf hitch!` supporti zrliavingstub.` axles 241 extendingV laterally' therefroml and a pair of y load supporting Wheels 2`3 rotatably? mounted on the stub axles 24. The trailer hitcllsupport alsov includes a cradle 26 which supports? a1 horizontal hitch 27. Connected to the horizontall hitch. 21 and: Working'with the latter isa vertical `hit'chl28. Theipedi estaliZZ of trailer 15'? is connectedV tofv'e'rticalhitch'' of theloa'd supporting structure 20 in` vertically: rigid and horizontally swingable relationship. Although'ihorizonti liitcirs'z is rigidly held onlstructurelagainst fore and aftpivotal movement, it allowsindependent'lateralivotl ingjo' theftrailer unit and therebyfred'uces- Strain'son the" earth?n mover andv rough riding characteristics:Y whenf the vehicle is` operating over roughvunevenf terrain Referring also to Fig. 2 the tractor? 10i' isi connected tobtherload supporting structure 20 in' verticallyl rigidi andi horizontally swingable relation tofone anotherfbyf axforle frame? having.` apedestal portion. 311 which is=-v engaged.`

witlz'rtlielhitchls of-the tractor 10'.. Extending fromzthe portion off'the rfork frameisf af pair? oflbra'ncheshydraulic rain and' to anabutting. position with the" cradle; 26 cor-'respondingto the weight'` transferring positionL oli theram 38. i

The operation; of the weight` transferringI supporting structure is illustrated in: Figs. l., 3= and 4.- Referring now" to Figs.4 l and 3 the load supporting structureis'- mounted intermediatethe relatively small size' tractor unit and the `oversized trailer unit. WithI the load sup#-V porting structure'20 mounted the' loadv which would-other-A Y w-isef bef carried on: the' tractorvslload supporting parts would thus be carried bythe load: supporting; structure; This* permits the earth mover to operate fully loaded? and-l at higlr speeds withoutv subjecting., the tractorsY load# supporting. parts-to dynamic loadscaused by the bouncing; ofthe-vehicle as itis operated over rough terrain.-v At this point of operation the ramhas been contracted and` is in its nonweight transferring position; The lever armi 39 is? correspondingly in. its-nona'butting'` position inirelationft'of the' cradle 26. With@ theranrand the' lever arm! ini their respective positions thevveight transferringrmeans is-complet'ely inactive. When the earth mover isY travelling over' terrain in'4 which sutlicienttractionv isl being supplied;even'thoughl the tractor andA trailer units' are oscillat-1 v ing relative tof' one another, the rarn willy remain con' tracted and the parts of thei will not be'A subjected tolany: reciprocating:` movement ofi the piston. Nory will a@ sudden? bounce ot? the earthI mover cause a suddenA bulidup` on pressure in-the ram thereby causing the ram' to: iritterfei'ewithl the operation of the earth mover.-

Referring:` now to' Fig. 4;. when the tractor unit has` insufficienti tractioni due to insuicient .weighton the' traction1wlieels,;the1ra1n 38is` selectively supplied fluidA pressure' causing: the-ram to'expand and moving the-lever arm:39tofits'fabuttinglposition withltho cradle 26 correan sponding.r to theframlsi weiglltiy transferring' position: hereinbefore described: the'tractor'i and trailerVv unite-ar' eacl respectively connected tothet loadf supporting: struc'- turei in vertically.- rigid; andl horizontally swingahle-- rela# tion.` t'o th'el load supporting'1 structu're 20;- Further ex.` tensioni ofthe hydraulic ram: 38A` isaccommodatedby counterc'lockwisei rotation of the t'ractor 10 about its* wheel 11 andi bye a clockwise'v rotationof thetrailer! uniti abouti its wheel axis'fzll. 'Eins'.` relative rotation'.1 of. the tractor and trailerunits' about. their axes? 11 and 21; respectively tends tovraise" the load supporting structure vertically about axis 36 thereby reducing-i ground weight on: the latten' This Weightli tiarisfer-fedi:t'ofthe'V tractor andtrailerunitsrw'itli l tlieinia'jorityof-l the weight tbeingtransferredrtothe tractor i uniti Since'tr'action'isaproductloffweight on; the dri'v ingf Wheels: and-1 the: traction factor of'A the' tires to the ground; the weight: tran'fsferred to` thef tractor unit'A insures tors load supporting parts. Therefore vthe load trans-` ferred to the tractor unit permits development of a sucient amount of traction to continue the effective operation of the earth mover, while maintaining a safe load on the load supporting parts of the tractor.

In accordance with my invention there is provided a load supporting structure positioned intermediate a relatively small size two wheel tractor unit and an oversized two wheel trailer unit which carries the load which would otherwise be placed on the tractors load supporting parts. The mounting of the load supporting structure permits the earth mover to operate without subjecting thev load supporting parts of the tractor unit to excessive stresses and thus endangering the safeness of the operation of the earth mover. Also, there is provided a weight transferring means selectively operable to transfer weight from the load supporting structure to the tractor unit when the earth mover becomes stalled due to the traction wheels of the tractor unit being unable to maintain a suiiicient amount of traction to effectively operate the earth mover. The weight transferring means includes a hydraulic ram that is so positioned that the oscillation of the tractor and trailer units relative to one another will not have any adverse eifects upon the rams working parts as the vehicle is operated over bumpy terrain. Thus there is achieved a weight transferring means which is capable of selectively transferring a portion of the load carried by the load supporting structure to the tractor unit when additional traction is required for continued eiective operation of the vehicle.

While only one particular embodiment of the applicants invention has been described, it should be understood that the applicants invention is not restricted.

thereto, that it is intended to clover all modifications of the invention which would be apparentl to one skilled in the art that come within the scope of the appended claims.

What is'claimed is:

1. An earth moving vehicle comprising: a two Wheel tractor unit; a hitch member connected on said tractor unit for rocking movement about a longitudinal pivot axis; a wheel supported trailer unit; and a load supporting structure positioned intermediate said tractor and trailer units including a trailer hitch support, a pair of load bearing wheels rotatably mounted on said trailer hitch support, hitch means for connecting said trailer hitch support to said trailer unit so that the latter is held against pivotal fore and aft movement with respect to the hitch support but is horizontally swingable with respect to the hitch supoprt, a frame having one end pivotally connected in vertically rigid, horizontally swingable relation to the hitch member on said tractor unit and the other end of said frame being pivotally connected to said trailer hitch support for vertically swinging movement about a transverse axis, and power means disposed between and connected to said frame and trailer hitch support for pivoting the latter relative to said frame about said transverse axis, said power means being eiective upon actuation to transfer weight lfrom said load bearing wheels to said tractor and trailer units.

2. An earth moving vehicle comprising: a two wheel tractor unit; a hitch member connected on said tractor unit for rocking movement about a longitudinal pivot axis; a wheel supported trailer unit; and a load supporting structure positioned between said tractor and trailer units including a trailer hitch support, a pair of load bearing wheels rotatably mounted on said trailer hitch support, hitch means for connecting said trailer hitch support to said trailer unit so that the latter is held against fore and aft pivotal movement with respect to the hitch support but is horizontally swingable with respect to the hitch support, a frame having one end pivotally connected in vertically rigid, horizontally swingable relation to the hitch member on said tractor unit and the other end of said frame being pivotally connected to said trailer hitch support for vertically swinging movement about a transverse axis, a lever arm having one end pivotally'V connected to said trailer hitch support for pivotal move-Y position for pivoting said trailer hitch support relative Y to said frame about said transverse axis and being effective to transfer weight from said load bearing wheels to said tractor and trailer units.

3. An earth moving vehicle comprising: a two wheelY tractor unit; a hitch member connected on said tractor unit for rocking movement about a longitudinal pivot axis; a Wheel supported trailer unit; and a load supporting structure positioned intermediate said tractor and trailer units including atrailer hitch support, a pair of load bearing wheels rotatably mounted on said trailer hitch support, hitch means connecting said trailer hitch support to said trailer unit so that the latter is held against fore and aft pivotal movement with respect to the hitch support but is horizontally swingable with respect to the hitch support, a fork frame having a pedestal portion pivotally connected in vertically rigid, horizontally swing-l able relation to the hitch member on said tractor unit and having a pair of branches extending from said pedestal portion, said branches each pivotally connected to said trailer hitch support for vertical swinging movement about a transverse axis, and power means disposed between said branches and connected to said pedestal and 30' trailer hitch support for pivoting the latter relative'to said fork frame about said transverse axis, saidpower m'eans being etective upon actuation to transfer weight fromusaid load bearing wheels to said tractor and trailer units. Y

4. An earth moving vehicle comprising: a two wheel tractor unit; a hitch member connected on said tractor unit for rocking movement about a longitudinal pivot axis; a wheel supported trailer unit; and aload supporting structure positioned intermediate said tractor and.

trailer'units including a trailer hitch support, a pair of load bearing wheels rotatably mounted on said trailer hitch support, hitch means connecting said trailer hitch support to said trailer unit so that the latter is held against fore and aft pivotal movement with respect to the hitch support but is horizontally swingable with respect to the hitch support, a fork frame having a pedestal portion pivotally connected in vertically rigid, horizontally swingable relation to the hitch member on said tractor unit and having a pair of branches extending from said pedestal portion, said branches each pivotally connected to said trailer hitch support for vertically swinging movement about a transverse axis, a lever arm disposed between said branches having one end pivotally connected to said trailer hitch support for pivotal movement to an abutting position with said trailer hitch support, and power means disposed between and connected to said pedestal and lever arm, said power means upon actuation vstructure positioned intermediate said tractor and trailer units including a trailer hitch support, a pair of load bearing wheels rotatably mounted on said trailer hitch support, hitch means connecting said trailer hitch support to said trailer unit so that the latter is held against fore and aft pivotal movement with respect to the hitch support but is in horizontally swingable relationship with the hitch support, a fork frame having a pedestal pivotally connected in vertically rigid, horizontally swingable 

